The invention relates to a powder-metallurgy produced high-speed steel article characterized by high hardness and wear resistance, particularly at elevated temperatures, suitable for use in the manufacture of gear cutting tools, such as hobs and other tooling applications requiring very high wear resistance.
In tooling applications requiring high hardness and wear resistance where the tool during use is subjected to elevated temperatures exceeding about 1000.degree. F. and up to for example 1200.degree. F., it is typical to employ carbide material for the manufacture of these tools. Carbide material, however, has the significant disadvantage of being difficult to machine to the desired tooling configurations, particularly intricate cutting surfaces, and is characterized by relatively poor toughness, which renders the tool made therefrom susceptible to cracking and chipping during use. In these applications, it is desirable to employ high speed steels, rather than carbide materials, because high speed steels are easier to machine to the desired tooling configuration and exhibit much higher toughness than carbide materials. High speed steels have not been used in these applications, however, because they do not exhibit the necessary hardness, and thus wear resistance, at the elevated temperatures in which conventional carbide tools are employed.
It is accordingly an object of the present invention to provide a powder metallurgy produced high-speed steel article useful for the production of gear cutting tools, such as hobs and other tooling applications requiring high wear resistance. The material shall be capable of attaining and maintaining high hardness at the elevated temperatures anticipated in carbide cutting tool applications and yet have the benefit of high-speed steels from the standpoint of toughness and machinability.